Alright, so, I'm working on a Compaq Presario Laptop, CQ50 model. It's obviously an older model and I'm not the first one to have cracked this thing open to take a look inside. Anyways, the problem is that the screen simply won't show any picture. I honestly don't know how to elaborate anymore than that. Otherwise, the computer itself seems to turn on just fine.
Also, as I said earlier, I'm not the first one to have worked on this laptop. Once I had gotten to the motherboard I found a small piece of cardboard wedged between the CPU/heatsink, i think(?), and the motherboard. Strange, but according to the previous owner this had "solved" their for a short time. However, here I am asking for your assistance.
I have the same problem with the same laptop currently. Not sure if you ever found a solution to this as i know it was some time ago that you posted.
These laptops have a common problem with the graphics card. The solder that connects the graphics chip gets hot and breaks the connection. This stops the screen and sometimes the laptop powering on. I have performed something called re flow on the graphics chip and brought the laptop back from the dead. However its still very temperamental. some times it takes 10 minutes just to get to the post screen. So i feel i have fixed on issue and found yet another. I have disconected the battery for some time inorder to reset the cmos but other than this i am stumped on a solution. I may just have to sell for parts :-/ Lesson learned for its owner DONT BUY A HP/ COMPAQ WITH THE NVIDIA GFORCE CARD
This could be the old HP disastrous trip into using lead-free solder which melted in laptops which got too hot. They blamed everyone but themselves but replaced motherboards, even out of Warranty. Search their website for the known problem and put in your serial number and you may still find that they will accept it back for a free repair.
That said, and as you noted in your post, it was some time ago so I'll close this thread now. If you find a fix, please start a new thread.